Two-position controllable pitch propeller



Sept. 30, 1947.

R. E." DA Y TWO POSITION CONTROLLABLE PITCH PROPELLER Fil ed Jan. 25, 1946 2 Sheets-Sheet l Inventor Sept. 30, 1947. R. E. DAY

' TWO POSITION CONTROLLABLE PITCH PROPELLER 2 Sheets-Sheet '2 Filed Jan. 25, 1946 Patented Sept. 3%, 1947 ,izscs 'EWQ-POSITIGN CONTROLLABLE PITCH IROPELLER Robert E. Day, Detroit, Mich.

Application January 25, 1946, Serial No. 643,333

4 Claims. i

This invention relates to improvements in controllable pitch propellers for airplanees, and more particularly to a two pitch propeller.

An object of the invention is to provide an improved two-position controllable pitch propeller for airplanes which will include means operable by a pilot for changing the pitch of the propeller from low to high pitch and vice versa.

Another object of the invention is to provide an improved two-position controllable pitch pro peller for airplanes which will include means operable by a pilot to change the pitch of a propeller from low to high pitch, and means for automatically changing the pitch of the propeller back from high to low pitch when the engine R. P. M. drops below cruising speed.

A further object of the invention is to provide an improved two-position controllable pitch propeller for airplanes which will include means for manually changing the pitch of the propeller from low to high pitch, and automatic means for returning the propeller from high to low pitch upon failure of the engine, or the dropping oi the engine R. P. M. below cruising speed.

A still further object of the invention is to provide an improved two-position controllable pitch propeller for airplanes which will be highly enicient in operation, and relatively inexpensive to manufacture and produce.

Other objects will appear as the description proceeds.

In the accompanying drawings which form a part of this application:

Figure 1 is a front elevation of the two-position controllable pitch propeller;

Figure 2 is a side elevation of the two-position controllable pitch propeller;

Figure 3 is a plan view looking down on the two-position controllable pitch propeller;

Figure 4 is a sectional view taken on the line 4-4 of Figure 2, and

Figure 5 is a sectional view taken on the line 5-5 of Figure 3.

Like characters of reference are used throughout the following specification and the accompanying drawings to designate corresponding parts.

In carrying out the invention, it will be understood that the improved two-position controlled pitch propeller will be mounted upon the shaft I of an airplane engine 2, of any suitable design. The propeller will comprise a hub portion 3, which Will be suitably secured to the engine shaft I, and will support the oppositely extending propeller blades 4 and 5 at its opposite ends.

Suitably mounted upon the forward surface of the propeller hub 3 are the spaced forwardly extended pivot or bearing rods 6 and 7, upon which the pitch controlling mechanism is mounted for movement, the same being controlled by the action of centrifugal force as the propeller blades are rotated at high speed.

Pivotally supported upon the pivotal bearing rods 6 and 1, are the frame members 8 and 9, which are provided with the three radially extending arms IE], II and 12. The arm 52 will be formed with the apertures l3 adjacent their outer ends, through which the blade movement limiting pins 14 extending from the hub 3 of the propeller will extend, and the oppositely disposed adjusting bolts I5 will extend from the opposite sides of the arms l2 into the said apertures is, to be adjusted to limit the degree of rotation between the said hub and the adjacent propeller blade.

The propeller blades A and '5 are secured to the opposite ends of the hub 3 in the customary manner and in case the blades are made of impregnated wood, rather than metal, there is provided at each end of the hub, the split bands I8 and i9 which will be clamped about the inner end of the wooden propeller blades and will support the outstanding pins 20 and 2!, which extend upwardly between the notched outer ends 22 and 23 of the said arms 12.

Substantially circular solid weights 2d and 25 are mounted upon the outer ends of the arms H of the frames 8 and it, while the hollow counter weights 26 and 21 are mounted upon the outer ends of the arms ill of the said frames 8 and 9. r

The connecting links 28 and 29 are connected between the said weights and counter weights, in such a manner that one weight on the frame 8 will be connected with the counter weight on the frame 9, and the counter weight on the frame 8 will be connected with the weight on the frame 9, whereby movement of the said frames and their associated parts will be equal and even, to cut down excess vibration when the engine and propellers are being operated.

A spinner ring Kill being substantially U-shaped in cross-section, and best illustrated in Figure 4 of the drawings, will be secured to the engine shaft 5', and will be provided with the oppositely and forwardly extending tubes 2H and 32, the same being connected respectively with the peripheral edges of the two hollow counter weights 26 and 21. A fluid supply tank (not shown) will be positioned within the airplane adjacent the pilots seat, and will contain suitable fluid with which to operate the hereinbefore described mechanism, and a pipe line 33 will extend from said tank to its discharge end which will lie within the hollow spinner ring, as best illustrated in Figure 4 of the drawings. A valve 3-4 will be positioned within said pipe line 33, and will be within reach of the pilot so that he may open the valve to admit fluid from the tank to the mechanism, and may close the valve when surficient fluid has been admitted to the pitch controlling mechanism. A balancing pipe 35 or tube will be connected between the two counter weights 26 and 21, so as to equalize the amount of fluid in said counter weights.

Each counter weight 26 and 21 will be provided with a discharge port 36, which will cooperate with the valve stem 3'! extending through the counter weight, said valve stem being provided with a spring controlling means at its outer end, the spring being designated by the reference numeral 38, and being held in the desired adjusted position by means of the nuts 39 and 40. A washer 4| will be secured to the valve stem 3? to limit its outward movement, and the inner ends of said valve stem will be formed with a conical head 42 adapted to seat within the discharge port 36 to close thesame when the mechanism is filled with liquid, and in operation.

It will be understood that for light and relatively inexpensive airplanes, the fluid used for operating the controllable pitch propeller will be water, and the water may be dumped or discharged through the discharge ports 35 in the counter weight 28 and 2'! when it is desired to change the pitch of the propeller blade from high to low pitch. However, in more expensive airplanes, and those which fly at high altitudes, it will be understood that the fluid will be such whose viscosity remains fairly constant, and will stand a temperature from 70 F. to 160 F. When using a fluid or liquid of this nature, it will have to be returned to the supply tank where it can be used again, and means will be connected with the discharge ports 36 whereby when the liquid is released from the counter weights 26 and 2?, it will be forced back into the supply tank. Any desired mechanism may be employed for returning the fluid to the tank, and such a mechanism has not been disclosed in the drawings.

The mode of operation of the improved twoposition controllable propeller will be readily understood from the drawings and from the description, but will now be described: Assuming that the tank which holds a supply of fluid is filled and the valve 34 is turned off, and that the airplane is flying along at cruising speed with the propeller blades in low pitch. When the pilot desires to change the pitch of the propeller blades from low pitch to high pitch, he merely opens the valve 34 in the pipe 33 from the tank and permits the fluid to run into the spinner ring 30, which is rotating at a high rate of speed with the propeller. Centrifugal force will throw the fluid through the tubing 31 and 32 to the hollow counter weights 26 and 21, respectively. It will be understood that when there is no fluid in the counter weights, the solid weights 24 and 25 will be heavier than the said counter weights and will throw the propeller blades into low pitch position. As soon as sufficient fluid enters the two counter weights 26 and 21 to make them heavier than the solid weights 24 and 25, the action of centrifugal force will move the frames 8 and 9 on the pivots 6 and 1 to engage the operating pins [4 to slightly rotate the blades 4 and to move them from their low pitch position to their high pitch position, in which position they will remain until the speed of the airplane drops below cruising speed, or until the pilot cuts down the speed of the engine considerably below the speed it runs when cruising. When the counter weights have sufiicient fluid in them to offset the weight of the solid weights, the pilot will close the valve 0 and the fluid will remain in the counter weights a long as it is desired that the propellers remain in high pitch position. The spring controlled valves in the counter weights are set so that the valves will remain closed while the airplane is travelling at cruising speed or above, but when the airplane drops below cruising speed, or when the pilot retards the speed of the engine, the pressure of the springs on the valves will overcome the pressure in the counter weights and will permit the valves to open and allow the liquid to escape. As soon as the liquid does escape, the counter weight will become lighter than the solid weights, at which time the centrifugal action of the solid weights will cause the rotation of the propeller blades to assume their low pitch position.

From the foregoing description it will be apparent that due to engine failure or any deliberate or unintentional slowing of the airplane engine will automatically cause the propeller to move from its high pitch position to its low pitch position, thereby assuring that the propeller pitch be correct for landing, regardless of whether or not the pilot remembers to manually effect the change. When a pilot is about to land his airplane he will have to reduce the engine R. P. M. far below cruising speed, but if he forgets to do this, the automatic action of the device will automatically return the propeller from the high pitch position to the safe low pitch position required when the airplane is landing. Consequently, one of the main advantages of this design is that the propeller will automatically go into low pitch, thereby requiring no special thought or action of the pilot.

While the preferred embodiment of the invention has been illustrated and described, it will be understood that it is not intended to limit the scope of the invention to this description as many minor changes in detail of construction may be resorted to without departure from the spirit of the invention.

Having thus described my invention what I claim as new and desire to secure by Letters Patent of the United States is:

1. A two-position controllable pitch propeller for airplanesjncluding a propeller hub, blades adjustably supported thereon, hollow counter weights connected with said blades, a fluid reservoir, valve controlled means connecting said reservoir with said hollow counterweights for admitting fluid into the same for shifting said blades by centrifugal action to high pitch position, and auxiliary counter weights functioning upon the release of the fluid from said first mentioned counter weights to return said blades to their low pitch position.

2. The subject matter as claimed in claim 1, and spring balanced valves in said counter weights for controlling the liquid therein.

3. The subject matter as claimed in claim 1, spring balanced valves in said counter weights for controlling the fluid therein, and synchronizing means connected between said counter weights.

4. The subject matter as claimed in claim 1,

2,428,308 5 and manually controlled means for varying the degree of change in pitch of said propeller blades.

ROBERT E. DAY.

Number 2,307,101 REFERENCES CITED 2,019,966 The following references are of record in the 2,039,720 file of this patent: 2,147,078

UNITED STATES PATENTS Name Date Blanchard et al. Jan. 5, 1943 Havill Nov. 5, 1935 Lambert May 5, 1936 Barish Feb. 14, 1939 

